LONDON EDF Energy is taking three of its nuclear reactors in Britain offline for inspection this week after finding a defect in a reactor of a similar design, the company said on Monday.
The firm, which operates 15 nuclear reactors in Britain, said it came across the defect on a boiler spine at its Heysham 1-1 reactor, which had been shut down in June for refuelling.
As a precautionary measure, EDF Energy is taking Heysham 1-2, Hartlepool 1 and Hartlepool 2 reactors offline from Monday to Wednesday for an estimated eight-week period.
This will mean that Britain will have a total of almost 3 gigawatts (GW) of nuclear capacity offline this week, about a third of Britain's total nuclear capacity.
However, because demand for power is quite low due to the summer and renewable energy output is quite strong, the impact on Britain's power supply should be muted, analysts said.
British baseload power prices for next week were trading 0.50 pounds higher at 13:00 PM BST at 36.50 pounds per megawatt hour.
British utility Centrica, which owns 20 percent of EDF Energy's nuclear plants, said the reduction in output from the nuclear fleet would reduce its earnings per share this year by around 0.3 pence.
A spokeswoman for parent company EDF told Reuters it was too early to comment on the possible impact on its earnings.
EDF Energy will lose around 2 terrawatthours (TWh) of production this year from the outages. The company had a record output of 60.5 TWh last year, the spokeswoman added.
Each reactor at the nuclear plants is surrounded by eight boiler units which create steam to drive the turbines. The boiler spine is a central metal tube inside the boiler which supports the weight of the boiler coiling tubes around it.
Routine inspections of other boiler spines have not previously indicated any similar defects, EDF Energy said.
The 610 megawatt (MW) Heysham 1-1 reactor near Lancaster will remain shut while an investigation takes place.
EDF Energy took its 620 MW Hartlepool 2 reactor offline on Monday morning for inspections. It will also take the second 610 MW reactor at Heysham 1 out of service on Wednesday and the 620 MW Hartlepool 1 reactor offline on Tuesday.
"EDF Energy has taken the conservative decision to shut down Heysham 1 Reactor 2 and Hartlepool Reactors 1 and 2 that are of a similar design over the next few days to carry out further inspections in order to satisfy itself and the regulator that the reactors can be safely returned to service," the company said in a statement.
Britain's Office for Nuclear Regulation said it was satisfied that EDF Energy was taking appropriate action to maintain nuclear safety.
"There has been no release of radioactive material and no persons have been injured," it added in a statement.
EDF Energy estimates the reactors will be offline for around eight weeks. Its other nuclear power stations are not affected by this issue because they are of a different design.
"Heysham 1 Reactor 1 is likely to continue to operate on reduced load when it returns to service until a suitable repair strategy can be implemented," the company statement added.
Two other EDF Energy nuclear units are already offline - Dungeness B21 and Hunterston B8 - due to maintenance and a statutory outage. Those units have a combined capacity of almost 1.2 GW.
Dungeness B21 is scheduled to come back online on Tuesday.
(additional reporting by Geert De Clercq in Paris; editing by Mark Heinrich)